1. Field of the Invention
The present invention relates to a method and apparatus for pre-heating water prior to the water entering a conventional residential gas or electric water heater. More particularly, the present invention relates to a method and apparatus for pre-heating water prior to the water being heated by a conventional gas or electric water heater by effecting a heat exchange between tap water and the hot air trapped in the attic of a conventional residential dwelling prior to the water being introduced to a conventional gas or electric water heater contained in the dwelling.
2. Description of the Prior Art
Conventional residential and commercial water heaters commonly receive water directly from a municipal or governmental water supply, or a private well. This water is commonly referred to as tap water. Tap water is normally relatively cool having a temperature generally less than 90.degree. degrees F. It is well known in the art that the higher the temperature of the water entering the hot water heater the less energy required to heat the water to a desired temperature for discharge from the hot water heater. Commonly, residential hot water heaters have a hot water discharge temperature of about 140.degree. degrees F.
Many devices have been disclosed in the prior art for utilizing a solar heat collector to supplement or in some cases replace the hot water heater in a residential dwelling. Exemplary of these patents are the following:
U.S. Pat. No. 3,989,032 discloses a system for solar heating of water in combination with a domestic hot water system having a hot water storage tank. The solar heater utilized has a surface which absorbs sunlight to produce heat, and a heat exchange passage for water in the solar heat collector.
U.S. Pat. No. 4,010,734 discloses a solar heating system including a solar collector, a water storage tank and water lines therebetween. The solar collector preferably includes a continuous length of the tubing coiled in a helical array of closely adjacent turns, having a water inlet communicating with the outermost turn and a water outlet communicating with the innermost turn. The solar collector is exposed to the direct rays of the sun and provides hot water for storage in a storage tank.
U.S. Pat. No. 4,153,955 discloses a solar heating device which utilizes a solar energy converter employing a stationary mirror which reflects and focuses solar radiation onto a tank of continuous radiation concentrators through which a liquid is selectively passed as the focussed radiation passes there across as the elevation of the sun changes during the day. This system provides for greater concentration of the rays of the sun on the solar energy converter throughout the course of the day.
U.S. Pat. No. 4,159,017 discloses a solar heating panel having a rectangular frame to receive a rectangular metal pan which supports a continuous coil of water tubing which is attached thereto by strips of metal attached to the pan. The solar heating panel is exposed to the direct rays of the sun and closed off by a pane of glass. The solar heating panel can be incorporated in a household water system and also to heat space.
U.S. Pat No. 4,191,329 discloses a hot water solar system which heats water in solar panels exposed to the direct radiation from the sun. From the solar panels the water is circulated through a supplemental heater and through a domestic heating system and thus made available for domestic use in washes and baths. In the event the solar panels will not increase the temperature of the water 11/2 degrees C. the water is not circulated through the solar panel but merely circulated back through the supplemental heater in the household loop.
U.S. Pat. No. 4,196,718 discloses a solar heating system for a building in which the liquid in the solar cell is subjected both to radiation from the sun and to heat from the exhaust chimney gases from the building furnace. The fluid in the tubes is heated by radiation and is circulated to a fluid reservoir where the fluid is drawn when required.
U.S. Pat. No. 4,257,397 discloses an apparatus for heating water with solar radiation incorporating an auxiliary heating unit external to the hot water reservoir and by- passing the solar heating element, for providing auxiliary water heating whenever the temperature in a selected portion of the reservoir decreases below a pre-determined level.
U.S. Pat. No. 4,368,549 discloses a swimming pool heater temperature control system designed to optimize the use of a conventional heater as a supplemental heat source for a solar heated swimming pool. The temperature control system operates by automaticaly adjusting the temperature setting of the heater to conform to the temperature vs. time profile of an optimum solar collector heating system.